The purpose of these studies is to attempt to define sites and mechanisms of altered renal function in experimental models in the rat which have reasonably similar clinical counterparts. Clearance, micropuncture and microdissection techniques will be utilized to study renal sodium retention in (1) a form of nephrotic syndrome in which glomerular filtration rate is normal and (2) after adrenal enucleation, a condition which leads initially to sodium retention and later to hypertension. BIBLIOGRAPHIC REFERENCES: Alexander, E.A., H.H. Bengele, and E.R. McNamara. Tubular function in rats with impaired natriuresis after adrenal enucleation. Clin. Res. 23: 354A, 1975. Migdal, S., E.A. Alexander, and N.G. Levinsky. Cardiac function and sodium excretion. Clin. Res. 23: 369A, 1975.